1. Field of the Invention
The present invention relates to pack trays for shipping integrated circuit chip packages, and in particular to a pack tray fabricated using interchangeable modules, thereby allowing different size packages to be secured in the same master frame.
2. Description of the Related Art
Pack trays for the shipment of integrated circuit chip packages are well known in the art. FIG. 1 illustrates a conventional pack tray 1 having apertures 2, ridges 3, and recessed areas 6 for securing chip packages 4. Specifically, the leads 4A of package 4 are positioned on the outside of ridge 3, whereas a raised portion (not shown) of package 4 which is formed on the underside of package 4 fits into aperture 2. Another pack tray (not shown) is placed on pack tray 1 after all chip packages 4 are positioned to ensure packages 4 and leads 4A are insulated from direct impacts and to prevent movement of chip packages 4 during shipment. Pack tray 1 further includes sections 5 which are solid pieces that provide a surface suitable for vacuum pickup of pack tray 1.
Pack tray 1 is fabricated in the following manner. A master mold is formed out of metal, then machined to provide apertures 2, ridges 3, and recessed areas 6. Finally, plastic is flowed around the master mold.
Because machining the master mold is expensive, manufacturers have typically fabricated pack trays to hold a large number of chip packages, i.e. between 15 and 40 chip packages, thereby reducing the shipping cost per chip package. However, some customers order only a few chip packages, while other customers order single chips in different package sizes, thereby dramatically increasing the shipping cost per chip package. Therefore, a need arises for a pack tray designed for a few chip packages and for a pack tray designed for different chip package sizes, both trays designed to minimize shipping cost per chip package.
In accordance with the present invention, a method of fabricating a pack tray for integrated circuit chip packages comprises the steps of: providing a master frame, providing a plurality of modules, and securing the plurality of modules in the master frame. Typically, each modular pack tray includes two types of modules: a chip module having an aperture therein to secure an integrated circuit chip package and a pick-up module for picking up the pack tray. In one embodiment, the pick-up module has a surface suitable for vacuum pick-up.
In one fabrication process in accordance with the present invention, the master frame and modules are machined from metal. To secure the modules in the master frame, plastic is then flowed around the plurality of modules positioned in the master frame.
In accordance with one embodiment of the present invention, the plurality of modules have an identical size. In other embodiments, at least one of the plurality of modules has a size different from at least one other of the plurality of modules. In yet another embodiment, a module includes lightening/stiffening sections.
The present invention significantly reduces the machining expense associated with prior art pack trays, thereby dramatically reducing the shipping cost per chip package, particularly in small shipments of chip packages. The present invention also provides shipping flexibility by allowing different size packages to be secured in the same pack tray. Moreover, the lightening/stiffening sections in accordance with the present invention significantly reduce the weight of a module as well as the cost of fabrication.